package tins2020

import (
	"log"
	"math/rand"
	"time"
)

type Game struct {
	Debug bool

	Balance          int
	Speed            GameSpeed
	SpeedBeforePause GameSpeed
	Herbarium        Herbarium
	Terrain          *Map

	tool          Tool
	centerChanged *Events
	toolChanged   *Events
	speedChanged  *Events
	simulation    Animation
}

type GameSpeed string

const (
	GameSpeedNormal GameSpeed = "normal"
	GameSpeedFast             = "fast"
	GameSpeedPaused           = "paused"
)

const simulationInterval = 120 * time.Millisecond
const fastSimulationInterval = 20 * time.Millisecond

func NewGame() *Game {
	game := &Game{
		centerChanged: NewEvents(),
		speedChanged:  NewEvents(),
		toolChanged:   NewEvents(),
		simulation:    NewAnimation(time.Millisecond * 10),
	}
	game.Reset()
	return game
}

func (g *Game) selectTool(t Tool) {
	g.tool = t
	g.toolChanged.Notify(t)
}

func (g *Game) setSpeed(speed GameSpeed) {
	if speed == g.Speed {
		return
	}
	if speed == GameSpeedPaused {
		g.SpeedBeforePause = g.Speed
	}
	g.Speed = speed
	g.speedChanged.Notify(speed)

	switch speed {
	case GameSpeedPaused:
		g.simulation.Pause()
	case GameSpeedNormal:
		g.simulation.SetInterval(simulationInterval)
		g.simulation.Run()
	case GameSpeedFast:
		g.simulation.SetInterval(fastSimulationInterval)
		g.simulation.Run()
	}
}

func (g *Game) tick() {
	randomNeighbor := func(pos Point) Point {
		switch rand.Intn(4) {
		case 0:
			return Pt(pos.X-1, pos.Y)
		case 1:
			return Pt(pos.X, pos.Y-1)
		case 2:
			return Pt(pos.X+1, pos.Y)
		case 3:
			return Pt(pos.X, pos.Y+1)
		}
		return pos
	}
	flowers := map[Point]Flower{}
	for pos, flower := range g.Terrain.Flowers {
		if rand.Float32() < flower.Traits.Spread {
			dst := randomNeighbor(pos)
			if _, ok := g.Terrain.Flowers[dst]; !ok {
				if _, ok := flowers[dst]; !ok {
					flowers[dst] = g.Terrain.NewFlower(dst, flower.ID, flower.Traits)
				}
			}
		}
		if Sqr32(rand.Float32()) < flower.Traits.Life*flower.Traits.LifeModifier {
			flowers[pos] = flower
		}
	}
	g.Terrain.Flowers = flowers
}

func (g *Game) CancelTool() {
	g.selectTool(nil)
}

func (g *Game) CenterChanged() EventHandler { return g.centerChanged }

func (g *Game) Dig(tile Point) {
	id := g.Terrain.DigFlower(tile)
	desc, ok := g.Herbarium.Find(id)
	if !ok {
		return
	}
	g.Balance += desc.SellPrice
}

func (g *Game) New() {
	g.Pause()
	g.Reset()
}

func (g *Game) Load() {
	g.CancelTool()
	g.Pause()

	var state GameState
	err := state.Deserialize(SaveGameName())
	if err != nil {
		log.Println("failed to load; error:", err)
		return
	}

	g.Herbarium = NewHerbarium()
	for _, flower := range state.Herbarium.Flowers {
		g.Herbarium.Update(flower.ID, func(desc *FlowerDescriptor) {
			desc.Unlocked = flower.Unlocked
		})
	}

	g.Balance = state.Balance
	g.Terrain = &Map{
		Temp:    NewNoiseMap(state.Terrain.Temperature),
		Humid:   NewNoiseMap(state.Terrain.Humidity),
		Variant: NewRandomNoiseMap(state.Terrain.Variant),
		PlaceX:  NewRandomNoiseMap(state.Terrain.PlaceX),
		PlaceY:  NewRandomNoiseMap(state.Terrain.PlaceY),
		Flowers: map[Point]Flower{},
	}
	for _, flower := range state.Terrain.Flowers {
		desc, _ := g.Herbarium.Find(flower.ID)
		g.Terrain.AddFlower(flower.Location, flower.ID, desc.Traits)
	}
	g.Terrain.Center = state.View.Center
	g.centerChanged.Notify(g.Terrain.Center)

	g.CancelTool()
	g.setSpeed(state.Speed)
}

func (g *Game) Pause() { g.setSpeed(GameSpeedPaused) }

func (g *Game) PlantFlower(id string, tile Point) {
	flower, ok := g.Herbarium.Find(id)
	if !ok {
		log.Println("user was able to plant a flower that doesn't exist")
		return
	}
	if flower.BuyPrice > g.Balance {
		// TODO: notify user of insufficient balance?
		return
	}
	g.Balance -= flower.BuyPrice
	g.Terrain.AddFlower(tile, id, flower.Traits)
}

func (g *Game) Reset() {
	g.Balance = 100
	g.Herbarium = NewHerbarium()
	g.Terrain = &Map{
		Temp:    NewNoiseMap(rand.Int63()),
		Humid:   NewNoiseMap(rand.Int63()),
		Variant: NewRandomNoiseMap(rand.Int63()),
		PlaceX:  NewRandomNoiseMap(rand.Int63()),
		PlaceY:  NewRandomNoiseMap(rand.Int63()),
		Flowers: map[Point]Flower{},
	}
	g.CancelTool()
	g.setSpeed(GameSpeedNormal)
}

func (g *Game) Resume() { g.setSpeed(g.SpeedBeforePause) }

func (g *Game) Run() { g.setSpeed(GameSpeedNormal) }

func (g *Game) RunFast() { g.setSpeed(GameSpeedFast) }

func (g *Game) Save() {
	state := g.State()
	err := state.Serialize(SaveGameName())
	if err != nil {
		log.Println("failed to save; error:", err)
	}
}

func (g *Game) SelectPlantFlowerTool(id string) {
	g.selectTool(&PlantFlowerTool{FlowerID: id})
}

func (g *Game) SelectShovel() {
	g.selectTool(&ShovelTool{})
}

func (g *Game) SpeedChanged() EventHandler { return g.speedChanged }

func (g *Game) State() GameState {
	var state GameState
	state.Balance = g.Balance
	state.Speed = g.Speed
	for _, id := range g.Herbarium.Flowers() {
		flower, _ := g.Herbarium.Find(id)
		state.Herbarium.Flowers = append(state.Herbarium.Flowers, HerbariumFlowerState{
			ID:       id,
			Unlocked: flower.Unlocked,
		})
	}
	flowers := make([]FlowerState, 0, len(g.Terrain.Flowers))
	for pos, flower := range g.Terrain.Flowers {
		flowers = append(flowers, FlowerState{ID: flower.ID, Location: pos})
	}
	state.Terrain = TerrainState{
		Temperature: g.Terrain.Temp.Seed(),
		Humidity:    g.Terrain.Humid.Seed(),
		Variant:     g.Terrain.Variant.Seed(),
		PlaceX:      g.Terrain.PlaceX.Seed(),
		PlaceY:      g.Terrain.PlaceY.Seed(),
		Flowers:     flowers,
	}
	state.View.Center = g.Terrain.Center
	return state
}

func (g *Game) TogglePause() {
	if g.Speed == GameSpeedPaused {
		g.Resume()
	} else {
		g.Pause()
	}
}

func (g *Game) Tool() Tool { return g.tool }

func (g *Game) ToolChanged() EventHandler { return g.toolChanged }

func (g *Game) UnlockNextFlower() {
	g.Herbarium.UnlockNext()
	g.selectTool(nil)
}

func (g *Game) Update() {
	for g.simulation.Animate() {
		g.tick()
	}
}

func (g *Game) UserClickedTile(pos Point) {
	if g.tool == nil {
		return
	}
	g.tool.ClickedTile(g, pos)
}